428 research outputs found

    Spectrometric performances of monocrystalline artificial diamond detectors operated at high temperature

    Get PDF

    Discriminatory diagnostic criteria for contourites with respect to other deepwater sedimentary facies

    Get PDF
    Bottom currents and a series of secondary oceanographic processes interact frequently at different scales to form distinct sedimentary deposits referred to as contourite and mixed (turbidite-contourite) depositional systems. These systems represent major depositional systems along the continental margins and abyssal plains of the world¿s oceans. A recent proliferation of both academic and industry research on deep-water sedimentation has revealed significant advances in the understanding of these systems, but non-specialists remain unaware of their sedimentary features and how they were formed. A paucity of examples in the ancient record and a lack of consensus regarding the diagnostic criteria used to characterise and differentiate them from other deep-water deposits limits our understanding of how they may record past processes, such as global oceanic circulation, tectonic events, gateway evolution, among others. In this work, examples of deep-marine deposits from onshore (Cyprus, Morocco, Spain, Italy and Angola) and offshore (Gulf of Cadiz, West Portugal, Mozambique, Antarctica, etc.) areas have been studied through a multidisciplinary approach to discriminate the main deep-water facies as contourites, pelagites/hemipelagites, turbidites, reworked turbidites and mass-transport deposits and determine why, when and how these deposits were formed in response to long-term tectonic history. The results described here highlight the importance of using primary sedimentary structures, microfacies and ichnological features as the best diagnostic criteria to distinguish reworked turbidites from contourites at the sedimentary facies scale. Diagnostic criteria for discriminating bottom current deposits include sedimentary condensation, reworking, reactivation surfaces, smaller grain-size variations, small-scale hiatuses, and omission surfaces. All of these vary according to the paleoenvironmental conditions, especially current velocities and sedimentation rates. Petrophysical properties of such deposits can furthermore make them extremely relevant as potential reservoirs in the context of energy geosciences

    Nuclear design of a shielded cabinet for electronics: The ITER radial neutron camera case study

    Get PDF
    The Radial Neutron Camera (RNC) is a diagnostic system located in ITER Equatorial Port #1 providing several spatial and time-resolved parameters for the fusion power estimation, plasma control and physics studies. The RNC measures the uncollided 14 MeV and 2.5 MeV neutrons from deuterium-tritium (DT) and deuterium deuterium (DD) fusion reactions through an array of neutron flux detectors located in collimated Lines of Sight. Signals from RNC detectors (fission chambers, single Crystal Diamonds and scintillators) need pre amplification because of their low amplitude. These preamplifiers have to be as close as possible to the detectors in order to minimize signal degradation and must be protected against fast and thermal neutrons, gamma radiation and electromagnetic fields. The solution adopted is to host the preamplifiers in a shielded cabinet located in a dedicated area of the Port Cell, behind the Bioshield Plug. The overall design of the cabinet must ensure the necessary magnetic, thermal and nuclear shielding and, at the same, satisfy weight and allocated volume constraints and maintain its structural integrity. The present paper describes the nuclear design of the shielded cabinet, performed by means of 3D particle transport calculations (MCNP), taking into account the radiation streaming through the Bioshield penetrations and the cross-talk effect from the neighboring Lower and Upper Ports. We present the assessment of its nuclear shielding performances and analyze the compliancy with the alert thresholds for commercial electronics in terms of neutron flux and cumulated ionizing dose

    Thick Film Morphology and SC Characterizations of 6 GHz Nb Cu Cavities

    Get PDF
    Thick films deposited in long pulse DCMS mode onto 6 GHz copper cavities have demonstrated the mitigation of the Q slope at low accelerating fields. The Nb thick films 40 microns show the possibility to reproduce the bulk niobium superconducting properties and morphology characterizations exhibited dense and void free films that are encouraging for the scaling of the process to 1.3 GHz cavities. In this work a full characterization of thick films by DC magnetometry, computer tomography, SEM and RF characterizations are presente

    The electron capture in 163^{163}Ho experiment – ECHo

    Get PDF
    Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the 3^{3}H β-decay and the 163^{163}Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in 163^{163}Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide 163^{163}Ho. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the 163^{163}Ho EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure 163^{163}Ho samples, the identification and suppression of background sources as well as the precise parametrization of the 163^{163}Ho EC spectrum are of utmost importance. The high-energy resolution 163^{163}Ho spectra measured with the first MMC prototypes with ion-implanted 163^{163}Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBq 163^{163}Ho will allow to reach a neutrino mass sensitivity below 10 eV/c2^{2}. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBq 163^{163}Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass

    Wegener's granulomatosis: an update on diagnosis and therapy

    Get PDF
    Wegener's granulomatosis (WG) is a unique clinicopathological disease characterized by necrotizing granulomatous vasculitis of the respiratory tract, pauci-immune necrotizing glomerulonephritis and small-vessel vasculitis. Owing to its wide range of clinical manifestations, WG has a broad spectrum of severity that includes the potential for alveolar hemorrhage or rapidly progressive glomerulonephritis, which are immediately life threatening. WG is associated with the presence of circulating antineutrophil cytoplasm antibodies (c-ANCAs). The most widely accepted pathogenetic model suggests that c-ANCA-activated cytokine-primed neutrophils induce microvascular damage and a rapid escalation of inflammation with recruitment of mononuclear cells. The diagnosis of WG is made on the basis of typical clinical and radiologic findings, by biopsy of involved organ, the presence of c-ANCA and exclusion of all other small-vessel vasculitis. Currently, a regimen consisting of daily cyclophosphamide and corticosteroids is considered standard therapy. A number of trials have evaluated the efficacy of less-toxic immunosuppressants and antibacterials for treating patients with WG, resulting in the identification of effective alternative regimens to induce or maintain remission in certain subpopulations of patients. Recent investigation has focused on other immunomodulatory agents (e.g., TNF-alpha inhibitors and anti-CD20 antibodies), intravenous immunoglobulins and antithymocyte globulins for treating patients with resistant WG

    Large-scale mass wasting in the western Indian Ocean constrains onset of East African rifting

    Get PDF
    Faulting and earthquakes occur extensively along the flanks of the East African Rift System, including an offshore branch in the western Indian Ocean, resulting in remobilization of sediment in the form of landslides. To date, constraints on the occurrence of submarine landslides at margin scale are lacking, leaving unanswered a link between rifting and slope instability. Here, we show the first overview of landslide deposits in the post-Eocene stratigraphy of the Tanzania margin and we present the discovery of one of the biggest landslides on Earth: the Mafia mega-slide. The emplacement of multiple landslides, including the Mafia mega-slide, during the early-mid Miocene is coeval with cratonic rifting in Tanzania, indicating that plateau uplift and rifting in East Africa triggered large and potentially tsunamigenic landslides likely through earthquake activity and enhanced sediment supply. This study is a first step to evaluate the risk associated with submarine landslides in the region

    A New Crocodylian from the Late Maastrichtian of Spain: Implications for the Initial Radiation of Crocodyloids

    Get PDF
    The earliest crocodylians are known primarily from the Late Cretaceous of North America and Europe. The representatives of Gavialoidea and Alligatoroidea are known in the Late Cretaceous of both continents, yet the biogeographic origins of Crocodyloidea are poorly understood. Up to now, only one representative of this clade has been known from the Late Cretaceous, the basal crocodyloid Prodiplocynodon from the Maastrichtian of North America.The fossil studied is a skull collected from sandstones in the lower part of the Tremp Formation, in Chron C30n, dated at -67.6 to 65.5 Ma (late Maastrichtian), in Arén (Huesca, Spain). It is located in a continuous section that contains the K/P boundary, in which the dinosaur faunas closest to the K/P boundary in Europe have been described, including Arenysaurus ardevoli and Blasisaurus canudoi. Phylogenetic analysis places the new taxon, Arenysuchus gascabadiolorum, at the base of Crocodyloidea.The new taxon is the oldest crocodyloid representative in Eurasia. Crocodyloidea had previously only been known from the Palaeogene onwards in this part of Laurasia. Phylogenetically, Arenysuchus gascabadiolorum is situated at the base of the first radiation of crocodyloids that occurred in the late Maastrichtian, shedding light on this part of the cladogram. The presence of basal crocodyloids at the end of the Cretaceous both in North America and Europe provides new evidence of the faunal exchange via the Thulean Land Bridge during the Maastrichtian
    corecore